<!DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">

<title>Hello World</title>
  <!-- 新 Bootstrap 核心 CSS 文件 -->
  <link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">

</head>

<body>
  <div class="text-center">
    <h1>Hello World</h1>
    <button class="btn btn-primary">我是按钮,按我一下!</button>
  </div>
  <script src="//cdn.bootcss.com/jquery/1.11.1/jquery.min.js"></script>
  <script src="//cdn.bootcss.com/bootstrap/3.2.0/js/bootstrap.min.js"></script>

</body>
</html>